Cell surface receptors are, in general, excellent and validated drug targets. nAChRs comprise a large family of ligand-gated ion channels that control neuronal activity and brain function. These receptors have a pentameric structure. In mammals, this gene family is composed of nine alpha and four beta subunits that co-assemble to form multiple subtypes of receptors that have a distinctive pharmacology. Acetylcholine is the endogenous regulator of all of the subtypes, while nicotine non-selectively activates all nAChRs.
The α7 nAChR is one receptor system that has proved to be a difficult target for testing. Native α7 nAChR is not routinely able to be stably expressed in most mammalian cell lines (Cooper and Millar, J. Neurochem., 1997, 68(5):2140–51). Another feature that makes functional assays of α7 nAChR challenging is that the receptor is rapidly (100 milliseconds) inactivated. This rapid inactivation greatly limits the functional assays that can be used to measure channel activity.
Recently, Eisele et al. has indicated that a chimeric receptor formed between the N-terminal ligand binding domain of the α7 nAChR (Eisele et al., Nature, 366(6454), p 479–83, 1993), and the pore forming C-terminal domain of the 5-HT3 receptor expressed well in Xenopus oocytes while retaining nicotinic agonist sensitivity. Eisele et al. used the N-terminus of the avian (chick) form of the α7 nAChR receptor and the C-terminus of the mouse form of the 5-HT3 gene. However, under physiological conditions the α7 nAChR is a calcium channel while the 5-HT3R is a sodium and potassium channel. Indeed, Eisele et al. teaches that the chicken α7 nAChR/mouse 5-HT3R behaves quite differently than the native α7 nAChR with the pore element not conducting calcium but actually being blocked by calcium ions. WO 00/73431 A2 reports on assay conditions under which the 5-HT3R can be made to conduct calcium. This assay may be used to screen for agonist activity at this receptor.
U.S. Pat. No. 5,977,144 discloses compositions for benzylidene- and cinnamylidene-anabaseines and methods for using these compositions for treating conditions associated with defects or malfunctioning of nicotinic subtypes brain receptors. These compositions target the α7 receptor subtype with little or no activation of the α4β2 or other receptor subtypes.
U.S. Pat. No. 5,919,793 discloses heterocyclic derivatives useful in lowering cholesterol levels in blood plasma.
U.S. Pat. No. 5,741,819 discloses arylsulfonylbenzene derivatives and their use as factor Xa inhibitors as being useful for the treatment of arterial and venous thrombotic occlusive disorders, inflammation, cancer, and neurodegenerative diseases.
U.S. Pat. No. 5,723,103 discloses substituted benzamides and radioligand analogs and methods of using the compounds for the identification of 5-HT3 receptors and the detection and treatment of abnormal conditions associated therewith.
U.S. Pat. No. 5,561,149 discloses the use of a mono or bicyclic carbocyclic, or heterocyclic carboxylic, acid ester or amide or an imidazolyl carbazol in the manufacture of a medicament suitable for the treatment of stress-related psychiatric disorders, for increasing vigilance, for the treatment of rhinitis or serotonin-induced disorders and/or coadministration with another active agent to increase the bioavailability thereof, or for nasal administration.
U.S. Pat. No. 5,273,972 discloses novel 2-substituted-3-quinuclidinyl arylcarboxamides and arylthiocarboxamides and corresponding arylcarboxylates which have utility as therapeutic agents which exhibit gastric prokinetic, antiemetic, anxiolytic and 5-HT (serotonin) antagonist effects in warm blooded animals.
U.S. Pat. No. 5,237,066 discloses enantiomers of absolute configuration S of amide derivatives of 3-aminoquinuclidine, the process for preparing them and their use as medicinal products having activity in respect of gastric movements and antiemetic activity.
U.S. Pat. No. 5,236,931 discloses novel 3-quinuclidinyl benzamides and benzoates which have utility as therapeutical agents which exhibit anxiolytic, antipsychotic, cognition improvement, antiemetic and gastric prokinetic effects in warm blooded animals.
U.S. Pat. No. 5,206,246 discloses anxiolytic-R-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamides and thiobenzamides, their N-oxides and pharmaceutically acceptable salts thereof. A preferred compound is R-(+)-4-amino-N-(1-azabicyclo[2.2.2]oct-3-yl)-5-chloro-2-methoxybenzamide.
U.S. Pat. No. 5,106,843 discloses heterocyclic compounds useful as 5-HT3 antagonists.
U.S. Pat. No. 5,084,460 discloses methods of therapeutic treatment with N-(3-quinuclidinyl)-2-hydroxybenzamides and thiobenzamides. The therapeutic agents are disclosed as exhibiting anxiolytic antipsychotic and cognitive improving effects in warm blooded animals.
U.S. Pat. No. 5,070,095 discloses novel 1-(azabicyclo[2.2.2]oct-3- or -4-yl)benzamides substituted on the benzene ring with the basic substituted aminomethyleneamino group which has been found to be useful in treating emesis, including emesis due to chemical and radiation anticancer therapy, anxiety, and impaired gastric emptying.
U.S. Pat. No. 5,057,519 discloses 5-HT3 antagonists as being useful in reducing opiate tolerance.
U.S. Pat. No. 5,039,680 disclose 5-HT3 antagonists in preventing or reducing dependency on dependency-inducing agents.
U.S. Pat. No. 5,025,022 discloses a method of treating or preventing schizophrenia and/or psychosis using S-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamides and thiobenzamides, their N-oxides and pharmaceutically acceptable salts thereof. A preferred compound is S(−)-4-amino-N-(1-azabicyclo[2.2.2]oct-3-yl)-5-chloro-2-methoxybenzamide.
U.S. Pat. No. 5,017,580 discloses memory enhancing-R-N-(1-azabicyclo[2.2.2.]oct-3-yl)benzamides and thiobenzamides, their N-oxides and pharmaceutically acceptable salts thereof. A preferred compound is R-(+)-4-amino-N-(1-azabicyclo[2.2.2]oct-3-yl)-5-chloro-2-methoxybenzamide.
U.S. Pat. No. 4,908,370 discloses anxiolytic-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamides and thiobenzamides as having anxiolytic activity, in particular, activity against anxiety induced by the withdrawal from ingested substances such as narcotics.
U.S. Pat. No. 4,877,794 discloses 2-alkoxy-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamide and thiobenzamide compositions and the use thereof to treat schizophrenia.
U.S. Pat. No. 4,877,780 discloses antiemetic N-substituted benzamides having pharmaceutical properties rendering them useful as antiemetic agents with reduced undesirable side effects.
U.S. Pat. No. 4,870,181 discloses a process for the preparation of 2-alkoxy-N-(1-azabicyclo[2.2.2])octan-3-yl)aminobenzamide.
U.S. Pat. No. 4,835,162 discloses agonists and antagonists to nicotine as smoking deterrents.
U.S. Pat. No. 4,820,715 discloses anti-emetic quinuclidinyl benzamides. The compounds are particularly useful in the treatment of chemotherapy-induced emesis in cancer patients. Some of the compounds are also useful in disorders relating to impaired gastric motility.
U.S. Pat. No. 4,803,199 discloses pharmaceutically useful heterocyclic acid esters and amides or alkylene bridged peperidines as serotonin M antagonists.
U.S. Pat. No. 4,798,829 discloses 1-azabicyclo[3.2.2]nonane derivatives having gastric motility enhancing activity and/or anti-emetic activity and/or 5-HT receptor antagonist activity.
U.S. Pat. No. 4,721,720 discloses a method of treating emesis, anxiety and/or irritable bowel syndrome.
U.S. Pat. No. 4,717,563 discloses 2-alkoxy-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamides and thiobenzamides in a method for alleviating emesis caused by non-platinum anticancer drugs.
U.S. Pat. No. 4,657,911 discloses 3-amino quinuclidine derivatives and the application thereof as accelerators of gastro-intestinal motor function and as medicament potentiators.
U.S. Pat. No. 4,605,652 discloses a method of enhancing memory or correcting memory deficiency with arylamido (and arylthioamido)-azabicycloalkanes, and the pharmaceutically acceptable acid addition salts, hydrates and alcoholates thereof.
U.S. Pat. No. 4,593,034 discloses 2-alkoxy-N-(1-azabicyclo[2.2.2]oct-3-yl)benzamides and thiobenzamides having gastrokinetic and anti-emetic activity.
U.S. Pat. No. 4,093,734 discloses amino-benzoic acid amides useful as anxiolytics, anticonvulsives, antiemetics and antiulcerogenics.
U.S. Pat. No. 3,702,324 discloses 3,4,5-trimethoxybenzamides of substituted anilines and of alkylpiperidines which exert a specific effect on the central nervous system and a somewhat lesser effect on muscle function, and thus have utility as tranquilizers.
WO 01/76576 A2 discloses a pharmaceutical composition for treatment of acute, chronic pain and/or neuropathic pain and migraines.
WO 01/60821 A1 discloses novel biarylcarboxamides and their use in therapy, especially in the treatment of prophylaxis of psychotic and intellectual impairment conditions.
WO 01/36417 A1 discloses novel N-azabicyclo-amide derivatives and use in therapy, especially in the treatment of prophylaxis of psychotic disorders and intellectual impairment disorders.
WO 00/73431 A2 discloses two binding assays to directly measure the affinity and selectivity of compounds at the α7 nAChR and the 5-HT3R. The combined use of these functional and binding assays may be used to identify compounds that are selective agonists of the α7 nAChR.
WO 92/15579 discloses multicyclic tertiary amine polyaromatic squalene synthase inhibitors and method of treatment for lowering serum cholesterol levels using the compounds.
WO 92/11259 discloses azabicyclic amides or esters of halogenated benzoic acids having 5-HT3 receptor antagonist activity.
FR 2 625 678 discloses N-(quinuclidin-3-yl)-benzamides and thiobenzamides useful as diet-control agents.
In Bioorg. & Med. Chem. Lett. 11 (2001) 319–321, the 5-HT3 antagonist tropisetron (ICS 205–930) is discussed as a potent and selective α7 nicotinic receptor partial agonist.
In Behavioral Brain Res., 113 (2000) 169–181, it is discussed that the brain α7 nicotinic receptor may be an important therapeutic target for the treatment of Alzheimer's disease using DMXBA which is known as GTS-21.